A tornado warning is a public warning that is issued by weather forecasting agencies to an area in the direct path of a tornado, or a severe thunderstorm capable of producing one, and advises individuals in that area to take cover. Modern weather surveillance technology such as Doppler weather radar can detect rotation in a thunderstorm, allowing for early warning before a tornado develops. They are also commonly issued based on reported visual sighting of a tornado, funnel cloud, or wall cloud, typically from weather spotters or the public, but also law enforcement or local emergency management. When radar is unavailable or insufficient, such ground truth is crucial. In particular, a tornado can develop in a gap of radar coverage, of which there are several known in the United States.
A severe thunderstorm warning is a type of public warning for severe weather that is issued by weather forecasting agencies worldwide when one or more severe thunderstorms have been detected by Doppler weather radar, observed by weather spotters, or reported by an emergency management agency, law enforcement, or the general public. Unlike a watch, a warning is issued to areas in the direct path of active severe thunderstorms, that are expecting a direct impact typically within an hour. Severe thunderstorms can cause property damage and injury due to large hail, high winds, and flooding due to torrential rainfall. The exact criteria to issue a warning varies from country to country.
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1891 until it adopted its current name in 1970.
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States, a government agency operating within the Department of Commerce as an arm of the National Oceanic and Atmospheric Administration (NOAA).
The Tornado outbreak sequence of March 9–13, 2006 was an early season and long lasting tornado outbreak sequence in the central United States that started on the morning of March 9 and continued for over four days until the evening of March 13. The outbreak produced 99 confirmed tornadoes, which killed a total of 10 people. The Storm Prediction Center (SPC) issued multiple elevated outlook throughout the sequence, including a rare high risk for March 12, which would end up being the most intense day of the outbreak, producing 62 in total. 11 F3 tornadoes were tallied, and a violent F4 tornado touched down in Monroe County, Missouri, becoming the strongest of the outbreak. Multiple tornado emergencies were issued for tornadoes throughout the outbreak as well. An intense F3 tornado that affected the towns of Renick and Maddison in Missouri killed 4 people and injured dozens others, becoming the deadliest of the sequence. Multiple of the tornadoes were long-tracked in nature, with 6 of them having paths exceeding 30 miles (48 km). One particular supercell thunderstorm during the outbreak persisted for many hours and progressed in excess of 800 miles (1,300 km) through Oklahoma, Kansas, Missouri, Illinois, Indiana, and extreme southern Michigan.
The tornado outbreak of January 1–2, 2006, was one of the largest tornado outbreaks ever recorded in the month of January. The outbreak affected much of the Central and Southern United States and produced 20 tornadoes. The tornadoes caused considerable damage in the states of Kentucky and Georgia. There were no tornado related fatalities and only minor injuries were reported.
In weather forecasting in the United States, "particularly dangerous situation" (PDS) is the wording used by the National Weather Service to convey special urgency in watch or warning messages for unusually extreme and life-threatening severe weather. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster. A watch or warning bearing the phrase is referred to as a PDS watch or PDS warning.
A tornado emergency is an enhanced version of a tornado warning, which is used by the National Weather Service (NWS) in the United States during imminent, significant tornado occurrences in highly populated areas. Although it is not a new warning type from the NWS, issued instead within a severe weather statement or in the initial tornado warning, a tornado emergency generally means that significant, widespread damage is expected to occur and a high likelihood of numerous fatalities is expected with a large, strong to violent tornado.
The Corn Belt derecho was a progressive derecho which affected a large area of the central United States on June 29, 1998. In the morning, thunderstorms, including a supercell, developed over South Dakota and tracked into central Iowa. As the thunderstorms reached central Iowa, a strong rear-inflow jet developed which caused the thunderstorm to take on a different characteristic, becoming a derecho. It traveled more than 600 miles in about ten hours, causing more than $125 million worth of widespread damage destruction, especially to crops, and was responsible for power outages to nearly a half a million people.
The Marion tornado outbreak was a small, severe tornado outbreak that affected southern portions of the Midwestern United States on May 29, 1982.
The 2009 Super Derecho was an extreme progressive derecho and mesoscale convective vortex (MCV) event that struck southeastern Kansas, southern Missouri, and southwestern Illinois on May 8, 2009. Thirty-nine tornadoes, including two of EF3 strength on the Enhanced Fujita Scale, were reported in addition to high non-tornadic winds associated with the derecho and MCV. Due to the abnormal shape of the storm on radar and the extremely strong winds, many called this an "inland hurricane." Notably, this storm had a defined eye akin to a tropical storm, which occurred alongside intense sustained winds of 70–90 mph (110–140 km/h) at the surface level, not associated with the bowing convection typical of a derecho. A new proper class of storm, the Super Derecho, has been used to describe this event after analysis in 2010. Embedded supercells produced hail up to baseball size in southern Missouri, a rare event in a derecho. A wind gust of 106 mph (171 km/h) was recorded by a backup anemometer at the Southern Illinois Airport after official National Weather Service equipment failed. This derecho was the last of a series of derechos that occurred at the beginning of May.
From May 3 to May 11, 2003, a prolonged and destructive series of tornado outbreaks affected much of the Great Plains and Eastern United States. Most of the severe activity was concentrated between May 4 and May 10, which saw more tornadoes than any other week-long span in recorded history; 335 tornadoes occurred during this period, concentrated in the Ozarks and central Mississippi River Valley. Additional tornadoes were produced by the same storm systems from May 3 to May 11, producing 363 tornadoes overall, of which 62 were significant. Six of the tornadoes were rated F4, and of these four occurred on May 4, the most prolific day of the tornado outbreak sequence; these were the outbreak's strongest tornadoes. Damage caused by the severe weather and associated flooding amounted to US$4.1 billion, making it the costliest U.S. tornado outbreak of the 2000s. A total of 50 deaths and 713 injuries were caused by the severe weather, with a majority caused by tornadoes; the deadliest tornado was an F4 that struck Madison and Henderson counties in Tennessee, killing 11. In 2023, tornado expert Thomas P. Grazulis created the outbreak intensity score (OIS) as a way to rank various tornado outbreaks. The tornado outbreak sequence of May 2003 received an OIS of 232, making it the fourth worst tornado outbreak in recorded history.
National Weather Service Lincoln, Illinois also known as National Weather Service Central Illinois is a weather forecast office responsible for monitoring weather conditions for 35 counties in Central and Southeastern Illinois. The Central Illinois office initially consisted of two forecast offices in Peoria and Springfield until the current location in Lincoln became the sole local forecast office in 1995. Federal meteorology offices and stations in the region date back to the 19th century when the Army Signal Service began taking weather observations using weather equipment at the Springer Building in Springfield. Since that time the presence of the National Weather Service greatly increased with the installation of new weather radars, stations and forecast offices. The current office in Lincoln maintains a WSR-88D (NEXRAD) radar system, and Advanced Weather Interactive Processing System (AWIPS) that greatly improve forecasting in the region. Lincoln is in charge of weather forecasts, warnings and local statements as well as aviation weather.
The December 17–22, 2012 North American blizzard was a winter storm that affected the Midwestern and Eastern United States. Forming on December 17, the winter storm moved across the midwest, forcing schools to close throughout the region. Numerous warnings and advisories had been posted by the National Weather Service for many states, including Iowa, Nebraska, Illinois, and Wisconsin. Both O'Hare International Airport and Midway International Airport in Chicago, Illinois canceled most departures and arrivals. According to flight tracking website FlightStats.com, more than 1,000 flights were canceled across the region. More than 130,000 customers were without power across the west and midwest.
National Weather Service - Norman, Oklahoma is a Weather Forecast Office (WFO) of the National Weather Service based in Norman, Oklahoma, which is responsible for forecasts and the dissemination of weather warnings and advisories for central and most of western Oklahoma, and western portions of north Texas. It is located in the National Weather Center on the University of Oklahoma campus, where it acts as one of the NOAA Weather Partners, a group of close-together weather-related agencies of the National Oceanic and Atmospheric Administration. NWS Norman is currently overseen by Mark Fox, who serves as the Meteorologist In Charge of the office.
National Weather Service - Pleasant Hill/Kansas City, Missouri is a Weather Forecast Office (WFO) of the National Weather Service, which is responsible for forecasts and the dissemination of weather warnings and advisories for 37 counties in northern and western Missouri and seven counties in extreme eastern Kansas, including the Kansas City and St. Joseph metropolitan areas. Though, as the Storm Prediction Center (SPC) in Norman, Oklahoma is responsible for issuing severe thunderstorm and tornado watches, the Pleasant Hill/Kansas City WFO only composes outline and status updates for SPC-issued watches affecting any portion of its designated County Warning Area.
The tornado outbreak of March 6–7, 2017 was a widespread severe weather and tornado outbreak that affected portions of the Midwestern United States in the overnight hours of March 6–7. Occurring just days after a deadly and more significant event across similar areas just a week prior, this particular outbreak led to 63 tornadoes within a 91⁄2-hour period as a quasi-linear convective system and discrete supercell thunderstorms traversed the region. The most notable aspect of the outbreak was an EF3 tornado that damaged or destroyed hundreds of structures within Oak Grove, Missouri, injuring 12 people but causing no fatalities. An EF1 tornado touched down near Bricelyn, the earliest known tornado on record in the state of Minnesota. Outside of tornadic activity, hundreds of damaging wind reports and a multitude of severe hail reports were documented.
The tornado outbreak of November 30 – December 2, 2018 was a late-season tornado outbreak that occurred across portions of the West South Central states and Midwestern United States. As a potent shortwave trough moved across the southern portions of the country, it was met with ample moisture return and destabilization, resulting in widespread severe thunderstorms that produced damaging winds, hail, and tornadoes. The event began late on November 30 in Oklahoma, spreading east and resulting in one fatality in Aurora, Missouri. Several tornadic supercells moved across portions of Illinois on December 1, and resulted in 29 confirmed tornadoes. This outbreak was the largest December tornado event on record in Illinois history, surpassing the December 1957 tornado outbreak sequence. The most significant tornado of the event was an EF3 that impacted Taylorville, Illinois, damaging or destroying hundreds of structures and injuring 22 people.
An intense derecho affected much of the Midwestern United States on August 10–11, 2020, primarily eastern Nebraska, Iowa, Illinois, Wisconsin, and Indiana. It caused high winds and spawned an outbreak of weak tornadoes. Some areas reported torrential rain and large hail.
Starting on the evening of July 13 and extending through July 16, 2024, an intense sequence of severe weather outbreaks affected much of the Midwestern and Northeastern United States. This included two significant derechoes that each had wind gusts exceeding 100 mph (160 km/h), as well as multiple tornado outbreaks that produced a combined 90 tornadoes across the affected areas. A ring of fire pattern fueled multiple systems that brought heavy rain and a tornado outbreak to northern Illinois, contributing to a partial dam failure in Washington County, Illinois, and multiple events of 90 mph (140 km/h) wind gusts. The sequence as a whole killed five people and injured three more.
